The present invention relates to flow scales for sensing the flow of solid materials.
In a variety of applications, it is frequently desirable to measure characteristics of a flow of solid materials, such as granular and powdered materials, without significantly interrupting the flow. Flow scale designs are known that incorporate an impact plate disposed substantially vertically, for example, U.S. Pat. No. 7,007,557 entitled “An Impact Flow Scale Having A Hingedly Suspended Impact Plate”. The flow of solid materials is directed against the impact plate whereupon a horizontal force component exerted upon the impact plate by varying densities and amounts of impacting material is detected by a force measuring device. When combined with weight data from another scale, information such as the flow rate and the weight of solid materials displaced can be determined.
Many prior art flow scales take up a relatively large amount of vertical space, which can limit their use for some applications. For example, some prior art flow scales can require 0.609-1.219 meters (2-4 feet) of vertical installation space. Provision of such a large amount of vertical installation space can necessitate undesirable facility redesign, including the burdensome task of raising existing structures to greater heights to accommodate the addition of a flow scale, making such devices costly and impractical to use. In particular, some prior art devices utilize a spreader cone that feeds a concave ring connected to a sensing device. However, such configurations generally require the sensing device to be located underneath the spreader cone, which tends to increase the vertical height of the device, particularly where the sensing device is a load cell not easily fit inside a cone. Moreover, locating a sensing device below a spreader cone requires routing wires away from a center of material flow, and efforts to protect such wiring from abrasive effects of the material flow can lead to measurement inaccuracies.
Thus, it is desired to provide an alternative flow scale with relatively compact vertical dimensions that still provides for relatively accurate and reliable flow sensing.